When downloading the files, an error occurs about the encoding of files. I fixed that.
A warning about the escape sequence in the code that showed the utility logo was fixed.
An error occurred when sending an epub to Kindle if content with a significant length had "display: none" as styling. I changed it to "visibility: hidden" to avoid that problem.
Fixed an error where SB_THEME_FILE (override_v1.css) was missing from the manifest.
Fixed a bug where the table of contents was not building correctly for Kindle. The problem was that the ID for the 'navPoint' was blank, which was the problem.
Added a feature to download the images mentioned in the CSS file and included these files to manifest correctly with the correct type.
The files were UTF-8, but the meta tag did not mention the encoding, causing gibberish characters on the Kindle device.
Adjusted the CSS file override_v1.css so the final epub generated has correct code snippets.
Fixed a bug where the cover page does not appear correctly on the Kindle device. The cover image's "content=" in meta did not mention the correct ID in the list.
I am fixing several bugs with this pull request.